Speaker
Description
Semianalytical quasinormal mode (QNM) computations have largely focused on quasinormal frequencies (QNFs), since constructing the eigenfunctions of the underlying QNM boundary-value problem is technically challenging. Yet in black hole merger events, identifying individual QNMs within the observed post-merger superposition of modes is essential for waveform modeling, tests of general relativity, and the broader black hole spectroscopy programme. Because mode identification depends on relative excitation, a precise and perturbation-independent quantification of QNM excitations is crucial. In this talk, we present a higher-order extension of the Dolan–Ottewill inverse multipolar expansion method, enhanced by corrections from from the WKB technique of Iyer and Will, which enables the systematic and efficient computation of QNMs and their quasinormal excitation factors (QNEFs). This framework substantially reduces errors - particularly at low multipolar numbers - while maintaining excellent agreement with computationally intensive methods, thereby offering a practical tool for future gravitational-wave modeling and tests of the no-hair conjecture.
